US4604549A - Orange-yellow emitting phosphor and cathode-ray tube employing the same - Google Patents

Orange-yellow emitting phosphor and cathode-ray tube employing the same Download PDF

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US4604549A
US4604549A US06/767,076 US76707685A US4604549A US 4604549 A US4604549 A US 4604549A US 76707685 A US76707685 A US 76707685A US 4604549 A US4604549 A US 4604549A
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phosphor
ray tube
orange
sub
phosphor according
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US06/767,076
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English (en)
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Naotoshi Matsuda
Masaaki Tamatani
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Toshiba Corp
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Tokyo Shibaura Electric Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
    • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
    • C09K11/7783—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing two or more rare earth metals one of which being europium
    • C09K11/7797—Borates

Definitions

  • This invention relates to an orange to yellow emitting phosphor. More particularly, it relates to an orange to yellow emitting phosphor useful for a cathode-ray tube used in office automation equipments, and also to a cathode-ray tube manufactured by employing the phosphor.
  • the flicker phenomenon will tend to be generated as the number of frames per second (frame frequency) is lower, and therefore displays may be sometimes practically useless in Europe where the frame frequency is lower (50 Hz) than those in Japan and the United States (60 Hz).
  • One means for resolving the above problem is to elongate the afterglow time of a phosphor.
  • the other means is to make the frame frequency higher. It is disadvantageous to high-frequency display to design an electrical circuit to make the frame frequency higher. It is desirable to use long-persistence (or afterglow) phosphor.
  • a cadmium containing phosphor as disclosed in British Pat. No. 495,706. This may be represented by the chemical composition of Cd 5 Cl(PO 4 ) 3 :Mn.
  • the time in which the fluorescent light intensity reaches 1/10 of the initial intensity after cessation of electron excitation (10% afterglow time) is as long as 25 to 30 milliseconds. In this case, even when the frame frequency may be as low as 50 Hz, it is possible to obtain a cathode-ray tube of an orange-emitting display without sensible flicker phenomenon.
  • the flicker phenomenon may sufficiently be alleviated if the 10% afterglow time of a phosphor is in the range from 10 to 100 milliseconds, particularly from 15 to 30 milliseconds. For this reason, the above-mentioned cadmium containing phosphor is practically useful.
  • a mixed phosphor wherein two or more kinds of emitting materials; for instance, europium-activated indium borate (red color) and terbium-activated indium borate (green color) disclosed in U.S. Pat. No. 3,394,084 may be candidates for these materials.
  • This mixed phosphor has a specific feature in that its emission color can be freely controlled by choice of the materials to be mixed on the one hand, but on the other hand it also involves the drawback that a constant uniform emission color can be obtained only with great difficulties.
  • An object of this invention is to provide an orange-yellow emitting co-activated phosphor which can give a desired emission color between orange and yellow and which does not include a harmful element in its chemical composition, and which can also provide a luminescent screen having excellent color purity, sufficiently long afterglow and high resolution.
  • FIG. 1 shows a front view of a cathode-ray tube for illustration of the chromaticity distribution on the luminescent screen of the cathode-ray tube;
  • FIG. 2 is an enlarged view of the phosphor particles for explanation of the relation between the phosphor particles and the chromaticity distribution;
  • FIG. 3 shows the emission spectrum of a phosphor according to the present invention.
  • This invention provides a phosphor capable of emitting from orange to yellow by varying the amounts of the activating elements incorporated, with a 10% afterglow time being 10 milliseconds or longer, and a cathode-ray tube employing the same.
  • the orange-yellow emitting phosphor comprises an europium and terbium co-activated indium borate represented by the chemical composition formula:
  • a and b are 0.0001 ⁇ a ⁇ 0.04, 0.0001 ⁇ b ⁇ 0.04.
  • the phosphor according to this invention is a co-activated phosphor comprising indium borate capable of emitting an intermediate color (orange-yellow) between the red color which is the emission color due to europium (Eu) and the green color which is the emission color due to terbium (Tb).
  • the fluorescent emission of the co-activated phosphor consists of the emission due to Eu and the emission due to Tb.
  • the 10% afterglow time is about 15 milliseconds, which is in conformity with one of the purposes of the present invention, namely the prevention of flicker.
  • a and b are 0.0001 ⁇ a ⁇ 0.04, 0.0001 ⁇ b ⁇ 0.04.
  • the activators are used in such large quantities that a and b each exceed 0.04, the interaction between Eu and Tb in the phosphor particle matrix will become undesirably too great, resulting in lowering of luminance. With such a phosphor, the object of this invention cannot be achieved. Moreover, the required emission color (orange-yellow) will become unpractically more reddish than is necessary.
  • the object of the present invention can be made more effective.
  • the emission color becomes too greenish or too reddish, respectively, outside the range of the emission color from orange to yellow of this invention, as opposed to the object of this invention.
  • an indium borate phosphor co-activated with Eu and Tb capable of emitting orange to yellow can be obtained.
  • an emission color between orange and yellow can freely be selected by varying the amounts of Eu and Tb incorporated at the ratio in the range as specified above to give good results when applied for a cathode-ray tube for office automation equipments.
  • the problem of environmental pollution or others can be removed by avoiding the use of cadmium compounds.
  • the colors all the emission colors between orange and yellow reducing fatigue of eyes and suitble for office automation equipments are rendered possible.
  • the 10% afterglow time is about 18 to 23 milliseconds, and the flicker phenomenon can sufficiently be reduced even at a frame frequency number of 50 Hz. More specifically, by co-activation with Tb of an Eu activated indium borate phosphor having a 10% afterglow time of about 15 millisceonds, there was obtained the result that the 10% afterglow time was improved by about 3 to 4 milliseconds. This is a very favorable fact for the present invention in the sense of accomplishing its object, and also it is one of the specific features of the invention.
  • the thus formed Eu, Tb co-activated indium borate phosphor was settled on the internal face of a 14 inch cathode-ray tube, followed by attachment by sealing of an electron gun to prepare a cathode-ray tube for an office computer.
  • the afterglow time was found as long as about 19 milliseconds.
  • Various phosphors co-activated with Eu and Tb were prepared according to the same procedure as described above in Example 1 by varying the amounts of the activators. That is, in the above composition formula (In 1-a-b Eu a Tb b )BO 3 , a and b were varied, to obtain the results as shown in Table 1. Further, for comparison, mixed phosphors comprising indium borate phosphors singly activated with Eu or Tb, and a Cd 5 Cl(PO 4 ) 3 : Mn phosphor are also shown.
  • Example 2 according to the present invention in which Eu and Tb have been made minimum and equal, has no problem in practical application.
  • Examples 3 and 4 in which Eu and Tb were increased in amounts, respectively, show higher relative luminance with the persistence characteristic being slightly improved.
  • the relative luminances are relatively lower but the afterglow time is as good as about 18 seconds, and they are also within the practical range.

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Luminescent Compositions (AREA)
US06/767,076 1982-12-07 1985-08-19 Orange-yellow emitting phosphor and cathode-ray tube employing the same Expired - Lifetime US4604549A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP57213308A JPS59105075A (ja) 1982-12-07 1982-12-07 蛍光体及びこれを用いた単色表示陰極線管
JP57-213308 1982-12-07

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US06557882 Continuation 1983-12-05

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US (1) US4604549A (ja)
EP (1) EP0111303B1 (ja)
JP (1) JPS59105075A (ja)
DE (1) DE3367611D1 (ja)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5132043A (en) * 1991-12-24 1992-07-21 Gte Products Corporation Method of preparing small particle size borate phosphor
US6596195B2 (en) 2001-06-01 2003-07-22 General Electric Company Broad-spectrum terbium-containing garnet phosphors and white-light sources incorporating the same

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL8500369A (nl) * 1985-02-11 1986-09-01 Philips Nv Kathodestraalbuis voorzien van een luminescerend indiumorthoboraat.
US5177401A (en) * 1988-12-05 1993-01-05 Hitachi, Ltd. Phosphor and cathode-ray tube using the same
DE69701030T2 (de) * 1996-08-30 2000-06-29 Koninklijke Philips Electronics N.V., Eindhoven Niederdruck quecksilber entladungslampe

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB495706A (en) * 1937-04-16 1938-11-16 Gen Electric Co Ltd Improvements in combinations of a source of radiation with material adapted to be excited to luminescence by the radiation
US3394084A (en) * 1965-08-30 1968-07-23 Gen Telephone & Elect Rare earth activated indium borate cathodoluminescent phosphors
US4005328A (en) * 1973-12-03 1977-01-25 U.S. Philips Corporation Mercury vapor discharge lamp for use in color copying by means of electrophotographic processes

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB495706A (en) * 1937-04-16 1938-11-16 Gen Electric Co Ltd Improvements in combinations of a source of radiation with material adapted to be excited to luminescence by the radiation
US3394084A (en) * 1965-08-30 1968-07-23 Gen Telephone & Elect Rare earth activated indium borate cathodoluminescent phosphors
US4005328A (en) * 1973-12-03 1977-01-25 U.S. Philips Corporation Mercury vapor discharge lamp for use in color copying by means of electrophotographic processes

Non-Patent Citations (6)

* Cited by examiner, † Cited by third party
Title
F. J. Avella et al., "Rare Earth Cathodoluminescence in InBO3 and Related Orthoborates", J. Electrochem. Soc., 114, 613 (1967).
F. J. Avella et al., Rare Earth Cathodoluminescence in InBO 3 and Related Orthoborates , J. Electrochem. Soc., 114, 613 (1967). *
F. J. Avella, The Cathodoluminescence of Terbium Activated Indium Orthoborate, J. Electrochem. Soc., 113, 1225 (1966). *
O. H. Schade, "Electro-Optical Characteristics of Television Systems," RCA Review 9, 245 (1945).
O. H. Schade, Electro Optical Characteristics of Television Systems, RCA Review 9, 245 (1945). *
Patent Abstracts of Japan, Unexamined Applications, C Field, vol. 6, No. 127, Jul. 13, 1982. *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5132043A (en) * 1991-12-24 1992-07-21 Gte Products Corporation Method of preparing small particle size borate phosphor
US6596195B2 (en) 2001-06-01 2003-07-22 General Electric Company Broad-spectrum terbium-containing garnet phosphors and white-light sources incorporating the same

Also Published As

Publication number Publication date
DE3367611D1 (en) 1987-01-02
EP0111303A1 (en) 1984-06-20
EP0111303B1 (en) 1986-11-12
JPS59105075A (ja) 1984-06-18
JPH0428758B2 (ja) 1992-05-15

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